Editing Lotus Improv (section)

==Concepts==

The core of what would become Improv was to separate the concepts of data, views of the data, and formulas into three portions.{{sfn|Abraham|Burnett|Erwig|2009|p=4}} The spreadsheet itself would contain only input data. Instead of referring to the data as, in effect, "the data that happens to be in these cells", each set of data in the sheet was given a name, and could then be grouped into categories. Formulas were typed into a separate section, and referred to data through their range, not their physical position in the sheets. Views of the data, some of which looked like spreadsheets, others like charts, could be created dynamically and were not limited in number.

To illustrate the difference between Improv and other systems, consider the simple task of calculating the total sales for a product, given unit sales per month and unit prices. In a conventional spreadsheet the unit price would be typed into one set of cells, say the "A" column, and the sales into another, say "B". The user would then type a formula into "C" that said "A1 times B1" (typically in a form such as <code>@times(A:1, B:1)</code> or <code>=A1*B1</code>). Then that formula must be copied into all of the cells in column C, making sure to change the reference to A1 to a new reference for A2, etc. The sheet can automate this to some degree, but the real problem is that it simply has no idea what the formula means. Any changes to the layout of the spreadsheet will often make the entire sheet stop working properly.

In Improv, one simply enters the data into columns called "Unit Price" and "Unit Sales". A formula can then be created that says "Total Sales = Unit Price times Unit Sales". Then if "Total Sales" view is added to the workbook, the totals would automatically appear there, because the sheet "knows" that is what the formula is for.

But the real power of Improv did not become clear until work had already started on the project. With the grouping system, one could collect monthly sales into groups like "1995" and "1996", and call the category "years". Then the unit prices could be grouped in terms of the product type, say "clothing" and "food". Now by dragging these groups around (represented by small tabs) the view could be quickly changed. This concept has later been implemented in the form of [[pivot table]]s in several products.